Infection, immune disturbances, and inflammation overlap in the ways that they damage tissues and promote development of cancer. Major studies under this project include the HIV/AIDS Cancer Match Study and Transplant Cancer Match Study, which link population-based registries of HIV infected people and transplant recipients to cancer registries in the U.S. Additional studies characterize risk factors for specific cancers in these immunosuppressed populations. Risk of non-Hodgkin lymphoma and lung cancer is elevated in immunosuppressed populations. Other cancers of interest, because they are associated with HIV or organ transplant, include Kaposi sarcoma, liver cancer, cancers related to human papillomavirus (such as cervical cancer and anal cancer), Hodgkin lymphoma, melanoma, non-melanoma skin cancers, kidney cancer, and multiple myeloma. Some studies under this project address the role of chronic infections, immune disturbance, and inflammation in these and other cancers. One study under this project is a case-control study of GB virus C and non-Hodgkin lymphoma. Other studies, which focus on cancer risk in the elderly, involve analyses of linked SEER Medicare registry data.